Two identical batteries each of e.m.f 2 V and internal resistance $1\, \Omega$ are available to produce heat in an external resitance by passing a current through it. The maximum power that can be developed across R using these batteries is
- 3.2 W
- 2.0 W
- 1.28 W
- $\frac{8}{9} W$
The Correct Option is B
Solution and Explanation
Hence power developed across the resistance R will be
$\, \, \, \, \, I^2R=\bigg(\frac{2E}{R+2r}\bigg)^2 \, \, R=\bigg(\frac{2 \times 2}{2+2}\bigg)^2 \times 2 = 2\, W$
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Concepts Used:
Electric Power
Power is defined as the rate of doing work. Electric power is the rate at which electrical energy is transferred through an electric circuit, i.e. the rate of transfer of electricity. The symbol for Electric Power is ‘P’. SI unit of electric power is Watt.
Electric Power Formula
P = VI
From Ohm's Law, V = IR
Hence, Power can also be expressed as P = I2R